[sushi] Don't assume X

[Cosimo Cecchi <cosimoc src gnome org>]

commit 020ed8545003b44d1bfae542b3965ddad473106a
Author: Matthias Clasen <mclasen redhat com>
Date:   Thu Nov 12 15:01:58 2015 -0500

    Don't assume X
    
    We must do a runtime check for X11, before calling gdk_x11 api.
    This does not fix sushi under Wayland, but it gets it far enough
    to show a window.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=758030

 src/libsushi/sushi-utils.c |   12 +++++++++---
 1 files changed, 9 insertions(+), 3 deletions(-)
---
diff --git a/src/libsushi/sushi-utils.c b/src/libsushi/sushi-utils.c
index e3e054d..ede75e8 100644
--- a/src/libsushi/sushi-utils.c
+++ b/src/libsushi/sushi-utils.c
@@ -25,7 +25,11 @@
 
 #include "sushi-utils.h"
 
+#include <gtk/gtk.h>
+
+#ifdef GDK_WINDOWING_X11
 #include <gdk/gdkx.h>
+#endif
 
 /**
  * sushi_create_foreign_window:
@@ -36,10 +40,12 @@
 GdkWindow *
 sushi_create_foreign_window (guint xid)
 {
-  GdkWindow *retval;
+  GdkWindow *retval = NULL;
 
-  retval = gdk_x11_window_foreign_new_for_display (gdk_display_get_default (),
-                                                   xid);
+#ifdef GDK_WINDOWING_X11
+  if (GDK_IS_X11_DISPLAY (gdk_display_get_default ()))
+    retval = gdk_x11_window_foreign_new_for_display (gdk_display_get_default (), xid);
+#endif
 
   return retval;
 }